C++ Multiple Choice Questions for Practitioners

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Question: 101

The v-table is per class and not per object

(A) True
(B) False

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Level: Practitioner

Category of MCQ: vtable in C++

Question: 102

dynamic_cast can be used only with pointers and references to objects

(A) True
(B) False

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Level: Practitioner

Category of MCQ: typecasting in C++

Question: 103

dynamic_cast is always successful when we cast a class to one of its base classes

(A) True
(B) False

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Level: Practitioner

Category of MCQ: typecasting in C++

Question: 104

When dynamic_cast cannot cast a pointer because it is not
a complete object of the required class it returns
a null pointer to indicate the failure

(A) True
(B) False

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Level: Practitioner

Category of MCQ: typecasting in C++

Question: 105

static_cast can perform conversions between pointers
to related classes not only from the derived class to its base,
but also from a base class to its derived

(A) True
(B) False

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Level: Practitioner

Category of MCQ: typecasting in C++

Question: 106

reinterpret_cast converts any pointer type to any other pointer type, even of unrelated classes

(A) True
(B) False

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Level: Practitioner

Category of MCQ: typecasting in C++

Question: 107

const_cast manipulates the constness of an object, either to be set or to be removed

(A) True
(B) False

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Level: Practitioner

Category of MCQ: typecasting in C++

Question: 108

Any object (built-in or user-defined) can be thrown

(A) True
(B) False

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Level: Practitioner

Category of MCQ: exceptions in C++

Question: 109

The formal parameter can be an ellipsis, in which case it handles all exceptions not yet handled

(A) True
(B) False

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Level: Practitioner

Category of MCQ: exceptions in C++

Question: 110

If not caught by handlers right after try block, exception moves to next-higher level and may be caught there

(A) True
(B) False

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Level: Practitioner

Category of MCQ: exceptions in C++

Question: 111

If no handler at any level catches the exception, terminate() will be called and program will terminate

(A) True
(B) False

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Level: Practitioner

Category of MCQ: exceptions in C++

Question: 112

void some_function() throw ();

How does above function behaves?

(A) Function declaration has error
(B) Behaviour is unknown
(C) Function will throw only standard exceptions defined in <exception>
(D) Function will not throw any exception

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Level: Practitioner

Category of MCQ: exceptions in C++

Question: 113

#include<iostream>
#include<string.h>
using namespace std;

int main()
{
    char one[]="one";
    char two[]="two";
    
    if(one==two){
        cout<<"Equal";
    }
    
    if(strcmp(one, two)==0){
        cout<<"Equal";
    }
    else
    {
        cout<<"NotEqual";
    }

    return 0;
}

(A) Equal
(B) EqualEqual
(C) EqualNotEqual
(D) NotEqual

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Level: Practitioner

Category of MCQ: conditional in C++

Question: 114

How this code would behave?

#include<iostream>
#include<exception>
using namespace std;

class cppbuzz{
    
public:
    cppbuzz(){
        cout<<"constructor.";
        int a; 
        throw a;
    }
    ~cppbuzz(){
        cout<<"destructor.";
    }
};

int main()
{
    cppbuzz *ptr = new cppbuzz();
    delete ptr;

return 0;
}

(A) Program is terminated without printing anything on console
(B) Prints 'constructor' and then it is terminated
(C) constructor.destructor. but ptr is never freed
(D) constructor.destructor. And ptr is freed

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Level: Practitioner

Category of MCQ: pointers in C++

Question: 115

Select true statement about weak_ptr of C++ 11

(A) C++11's weak_ptrs are used with shared_ptrs.
(B) C++11's weak_ptrs can be used without weak_ptrs
(C) C++11's weak_ptrs are replacement of unique_ptr
(D) C++11's weak_ptrs are used for unique ownership

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Level: Practitioner

Category of MCQ: pointers in C++

Question: 116

Select the false statement about shared_ptr

(A) We can only use these smart pointers to refer to objects allocated with new
(B) It is recommended that you do not use both 2 shared_ptr and raw pointer on the same object
(C) It can't be copied or assigned to another shared_ptr
(D) We can also reset a shared_ptr by assigning it the value nullptr

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Level: Practitioner

Category of MCQ: pointers in C++

Question: 117

Is there any error in following code?

unique_ptr<XYZ> ptr1 (new XYZ); 
unique_ptr<XYZ> ptr2(ptr1);

(A) This is valid code snippet with no error
(B) Error: Copy construction is not allowed at line 2
(C) Error: Assignment is not allowed at line 2
(D) Error: Runtime exception

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Level: Practitioner

Category of MCQ: pointers in C++

Question: 118

Which of the following Exception is thrown by C++ 'new'
when there is no memory available to allocate?

(A) bad_exception
(B) overflow_error
(C) out_of_range
(D) bad_alloc

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Level: Practitioner

Category of MCQ: new_delete in C++

Question: 119

// find the output of below program if user enters: 2 2 2
#include<iostream>
using namespace std;

class Rectangle
{
protected:
int length,width,area;
public:
void getdata()
{
cout<<"enter data :";
cin>>length>>width;
}
void print()
{
area=length*width;    
cout<<area;

}
};

class cube : public Rectangle
{
int height,volume;
public:
void getdata()
{
cout<<"enter height, length,width : ";
cin>>height>>length>>width;
}
void dprint()
{
volume=length*height*width;    
cout<<volume;
}
};

int main()
{
cube c;
c.getdata();
c.print();
c.dprint();
return 0;
}

(A) 08
(B) 04
(C) 84
(D) 48

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Level: Practitioner

Category of MCQ: inheritance in C++

Question: 120

//find the output of below c++ program

#include<iostream>
using namespace std;

class base{
    public: 
    void hello(){
        cout<<"base";
    }
};

class derived: private base{
    
};

int main()
{
derived obj;
obj.hello();
return 0;
}

(A) base
(B) Nothing is printed
(C) basebase
(D) None of the Above

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Level: Practitioner

Category of MCQ: inheritance in C++

Question: 121

#include<iostream>
using namespace std;

class cppbuzz_base{
    public: 
    
    void hello(){
        cout<<"Hello Base ";
    }
};

class derived: public cppbuzz_base{
    public:
    
    void hello(){
        cout<<"Hello Derived ";
    }
    
};

int main()
{
derived obj;
cppbuzz_base baseObj = cppbuzz_base(obj);
baseObj.hello();
return 0;
}

(A) Hello Derived
(B) Hello Base
(C) Hello Derived Hello Base
(D) Hello Base Hello Derived

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Level: Practitioner

Category of MCQ: typecasting in C++

Question: 122

#include<iostream>
using namespace std;

class cppbuzz_base{
    public: 
    
    void hello(){
        cout<<"Hello Base ";
    }
};

class derived: public cppbuzz_base{
    public:
    
    void hello(){
        cout<<"Hello Derived ";
    }
    
};

int main()
{
cppbuzz_base baseObj;
derived obj = derived(baseObj);
obj.hello();
return 0;
}

(A) Hello Derived
(B) Hello Base
(C) Hello Derived Hello Base
(D) Error: not matching func to call ‘derived::derived(cppbuzz_base&)’

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Level: Practitioner

Category of MCQ: typecasting in C++

Question: 123

//find the output of below code on Singleton class

#include <iostream>

class Singleton
{
    private:
        static Singleton* instance;
        Singleton();

    public:
        static Singleton* getInstance();
};

Singleton* Singleton::instance = 0;

Singleton* Singleton::getInstance()
{
    if (instance == 0)
    {
        instance = new Singleton();
    }

    return instance;
}

Singleton::Singleton()
{}

int main()
{
    Singleton* one = Singleton::getInstance(); 
    Singleton* two = Singleton::getInstance();

    if(one == two)
    std::cout<<"Both pointers hold same object";
    else
    std::cout<<"They don't hold same object";
    
    return 0;
}

(A) Both pointers hold same object
(B) They don't hold same object
(C) Compilation Error
(D) Exception occured

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Level: Practitioner

Category of MCQ: singleton in C++

Question: 124

Note: Mandatory steps to follow while declaring Singleton class

1. Private Constructor
2. Private Copy Constructor : Not Implemented
3. Private Assignment Operator: Not Implemented

(A)
(B)
(C)
(D)

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Level: Practitioner

Category of MCQ: singleton in C++

Question: 125

#include<iostream>

class cppbuzz{
    
  public:
        cppbuzz(){
            std::cout<<"cppbuzz";
        }
        ~cppbuzz(){
            std::cout<<"~cppbuzz";
        }
        
        virtual void myfunc() = 0;
};

int main(){
    cppbuzz obj;
    return 0;
}

(A) error: cannot declare variable ‘obj’ to be of abstract type ‘cppbuzz’
(B) cppbuzz
(C) ~cppbuzz
(D) cppbuzz~cppbuzz

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Level: Practitioner

Category of MCQ: abstract_class in C++

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